The present invention relates generally to heat transfer equipment, and more particularly concerns an apparatus that may be used for diverse heat transfer applications which range from transferring images from a release paper to a fabric (such as a T-shirt) to heat sealing packages, such as preformed blister packages for drugs. The invention will be specifically disclosed by way of example, in connection with an apparatus which is used to transfer images onto small pieces of fabric (such as a T-shirt). The potential use of the apparatus is, however, far more diversified.
Present heat transfer equipment for transferring images from release paper onto fabric, such as T-shirts, are of two general types. The first of these two types could be characterized as a clam shell design or a book type design. This equipment has a series of levers and links that attach to an upwardly moving hot plate which opens and closes above a lower permanent platen in a clam shell like manner. An operator will place a garment, such as a shirt, onto the top of the lower permanent platen (which may be covered by rubber or the like) and manually pivot the upward moving hot plate into contacting relationship with the lower platen. As the operator pulls a lever attached to the upper hot plate downwardly, the lever goes through a toggle action to provide adequate pressure between the hot plate and the lower platen. Present day machines of this design have several disadvantages. First of all, most of these machines are not made with great precision with the consequence that point loading frequently results when pressure is applied between the upper hot plate and the lower platen. With an uneven distribution of pressure throughout the transfer area, portions of the transfer with less than the maximum point pressure will be of low quality. With inadequate pressure at certain areas, the transfer may tend to bubble and eventually sever from the fabric.
The hot plate in the upper platen of the clam shell design rests at approximately a 30.degree. angle to the horizontal lower platen when in an open position. Thus, the hot plate is exposed to the environment during most of the operation time. When this hot plate is radiating heat into an air conditioned environment, such as a store, the operator must not only pay for the energy to generate the heat in the hot plate, but also to extract that heat from the environment through the air conditioner. This radiating hot plate is also disadvantageous in that this radiated energy tends to curl die cut letters which are arranged upon the lower platen of the machine. When such curling occurs, it is frequently the case that the hot plate will contact the corner of the curled letters prior to the rest of the letter when the platens are closed. A misalignment of the letters may result. Moreover, when the store operator is lettering or placing the die cut letters on a garment with such a machine, very little clearance is provided between the operator's knuckles and the hot plate. Since the hot plate may be between 350.degree.-375.degree. F., contact with the operator's skin may result in serious burns.
In the past, in an effort to overcome the burning of the operator's hands, a sleeve-like heat shield has been designed to put over the upper hot plate. With such a heat shield, the operator manually inserts the sleeve over the upper hot plate while the garment on the lower plate is being aligned for lettering. It is then necessary to manually remove the sleeve-like heat shield prior to closing the machine. Due to time and inconvenience required in placing the heat shield over the hot plate and subsequently removing it prior to actual operation of the equipment, many operators have opted to use the devices without heat shields.
Still further, many of these prior art machines, due to their complexity and moving parts, have been of questionable reliability. As a result, many store owners have resorted to the use of multiple machines in order to have backup capability in the event that the first machine becomes inoperative.
A second general type of machine commonly used for transferring images onto fabric has a vertical post and a hot plate which is swingingly cantilevered off the post. The operator places the garment on a platen with the hot plate swung to one side. When the garment and transfer are in proper placement on the lower platen, the hot plate is swung to a position above the garment and lowered thereon. These swinging cantilevered type machines are extremely heavy, space consuming, expensive and difficult to install.
The present invention provides a substantially smaller and less expensive piece of equipment which will perform the heat transfer applications of the machine discussed above with improved results. Applicant's invention is much more energy efficient and alleviates the need for cams, levers, gears and air cylinders to get the pressure required for applying heat transfers. The apparatus of the present invention is not limited to or controlled by the operator in any way and allows transfers of uniformly high quality. An apparatus embodying the invention may also be made relatively small and light so that it may be readily transported and utilized in a relative small space.
The present invention is also highly useful as a heat sealing machine for packaging material. A machine made in accordance with the invention would be capable of permanently attaching a peelable lidding material to a preformed blister for the unidose packaging of drugs, for example. Such a machine could be used by a local pharmacist or a pharmacist in a hospital for unit packaging of prescription drugs.
In many states, drugs sold to nursing homes must be unidose packaged before they are delivered to the nursing home. The equipment that is presently used for packaging this material is of an air cylinder platen press type design. The equipment, by its design, dictates that the pharmacist has a compressor, and that the machine be relatively heavy and cumbersome. A machine made in accordance to the present invention could be relatively small and placed upon a retail counter of a pharmacy. It could also be used in a hospital pharmacy for providing unidose packaging of medication for the various patients in the hospital.
Many hospitals today distribute unidose packages of medication. The present invention would permit a permanent seal for the packaging for the medication which would not be reclosable. It is common knowledge that hospitals presently experience substantial problems from pilferage of many drugs, particularly those drugs that have high black market values. It is possible, with the pressure sensitive packages that are presently used, for a hospital employee to open the pressure sensitive label, remove the drug (which may be a narcotic), replace the stolen drug with a placebo and reclose the package. With a permanent seal package such as would be possible with the present invention, it would be readily apparent if an unauthorized person tampered with the medication. Many times the switching of the drugs is not detected and the patient for whom the medication was prescribed is erroneously viewed as having failed to respond to the medication.
Accordingly, it is an object of the present invention to provide an improved heat transfer apparatus that will produce higher quality heat transfers at a lower cost.
It is a further object of the present invention to provide an apparatus that will achieve the required pressure to affectuate high quality heat transfers with the necessity of cams, levers, gears, and air cylinders.
It is yet another object of the present invention to provide a heat transfer apparatus that is not dependent upon the operator for application of pressure.
It is still another object of the present invention to provide a heat transfer apparatus of increased productivity.
It is yet another object of the present invention to provide a heat transfer apparatus that will minimize the physical space requirements needed for the apparatus and its operation.
Another object of the present invention is to provide a heat transfer apparatus that will operate more efficiently and use less energy than equivalent present day machines.
It is yet another object of the present invention to provide a heat transfer apparatus that is safe to operate.
It is yet a further object of the present invention to provide a heat transfer apparatus that may also be used for curing heat transfer images.
Still another object of the present invention is to provide a heat transfer apparatus that will apply a uniform pressure between a heating element and a heat transfer image.
It is yet a further object of the invention to provide a heat transfer apparatus that will enable high quality heat transfers on fabrics of irregular shapes with bulky sections.
It is still another object of the present invention to provide a heat transfer apparatus that may be used to seal packages.